Can anyone offer explanations please. This code did not work
quite as I expected. It's a test routine for checking WDT/b0 IRQ
on the F84

b0 - IRQ i/p (pushbutton, 10k pulldown, debounced). NB even though
        Option has been set for rising edge trigger, IRQ occurs on falling
        edge - comments ?)
b6 - red LED
b7 - green LED

The flow is - push button to generate IRQ. Red LED on for 2s,
red LED off for 2s, green LED on for 2s, exit. The middle
section (zzz3) does show a low power sleep on a meter so I
assume zzz2 and zzz4 sleeps are working too

During this time, I expected b0 IRQs to be disabled. However,
without the explicit "bcf inte", b0 IRQs can still occur, even
though they should have been turned off by an implicit "bcf gie"
on entry into the ISR. If the pushbutton is pressed while the
green LED is on, it goes off and the red comes on, showing that
ISR has been re-entered

With "bcf inte" included, b0 IRQs are disabled as I thought they
should have been. Why is this so ? I can find no reason for it in the
documentation (it could be my paperwork that's deficient). What
also puzzles me is why if the PB is pressed while the green LED is
on (and IRQs are supposedly inactive), after the green goes off, the
flow immediately goes back to lighting the red LED, ie an IRQ seems
to be stored for processing after the current ISR is done, so why does
the "bcf intf" have no effect (assuming intf had somehow been set) ?

TIA

  org irq
  goto isr

entry    movlw  00h        ;...o oooo
            tris   porta
            movlw  01h        ;oooo oooi
            tris   portb
            movlw  0c8h      ;pull-ups off, WDT, r/edge b0 INT
            option

            clrf   porta
            clrf   portb
            bsf    inte           ;enable b0 IRQ
            bsf    gie

zzz1        sleep               ;wait for IRQ
                nop
                nop
                goto   zzz1       ;loop if WDT, resume after isr

;IRQ routine

isr        bcf    intf
            bcf    inte

            bsf    rled            ;red on
            movlw  0a0h
            movwf  count
zzz2     sleep                  ;timeout1
            incfsz count,f
            goto   zzz2
            bcf    rled            ;red off

            movlw  0a0h
            movwf  count
zzz3     sleep                  ;timeout2
            incfsz count,f
            goto   zzz3

            bsf    gled           ;green on
            movlw  0a0h
            movwf  count
zzz4     sleep                  ;timeout3
            incfsz count,f
            goto   zzz4
            bcf    gled           ;green off
            bcf    intf
            bsf    inte
            retfie

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